Border control system for gas discharge display panels

ABSTRACT

In gaseous discharge display panels of the cross conductor matrix type the conductors are non-conductively coupled to a thin gaseous discharge medium, one technique for conditioning the data or information display sites in the panel for operation of uniform potentials is to maintain the border discharge sites in an on or fired condition. The invention is directed to an improved system for controlling the border sites of such panels and provides for a border writer for (1) sustaining the border, (2) writing the border (3) erasing the border during long idle periods to minimize aging (4) border conditioning (all four sides), (5) border firing at reduced frequency to reduce or minimize the effect of aging as an alternative to (3) and (6) sustaining the border at a slightly higher voltage level.

United States Patent [1 1 Miavecz BORDER CONTROL SYSTEM FOR GAS DISCHARGE DISPLAY PANELS Inventor: Joseph L. Miavecz, Toledo, Ohio Assignee: Owens-Illinois, lnc., Toledo, Ohio Filed: Dec. 23, 1971 Appl. No.: 211,371

References Cited UNITED STATES PATENTS 9/1971 Soltan 340/166 R 2/1972 Kupsky 3l5/l69 TV X 4/1972 Caras 315/169 TV X 4/1972 Caras et al. 315/169 TV X [111 3,786,484 [451 Jan. 15, 1974 Primary Examiner-David L. Trafton Attorney-Donald Keith Wedding et al.

[5 7 ABSTRACT In gaseous discharge display panels of the cross conductor matrix type the conductors are nonconductively coupled to a thin gaseous discharge medium, one technique for conditioning the data or information display sites in the panel for operation of uniform potentials is to maintain the border discharge sites in an on or fired condition. The invention is directed to an improved system for controlling the border sites of such panels and provides for a border writer for (l) sustaining the border, (2) writing the border (3) erasing the border during long idle periods to minimize aging (4) border conditioning (all four sides), (5) border firing at reduced frequency to reduce or minimize the effect of aging as an alternative to (3) and (6) sustaining the border at a slightly higher voltage level.

11 Claims, 29 Drawing Figures X ODD AODREMING PAIENIE JAN 1 s 2914 SHEET 3 [IF 5 Y m V 0 0 5 5 L s A 5 5 5 m V o V 0 5 V F Y Fla-3G BORDER. ERASE WA VEFORMS PATENTEDJAN l 5 i974 SHEET 5 BF 5 V TIME sum" YB VYB V -I-A o L L. V

TIME SHIFT X5 FOUR AXES BORDER COND/T/ON/NG WAVE FOR/M5 X SITE DISCHARGE A 3-|O VOLT'S ADJUSTABLE TF'L MEJ display purposes.

BORDER CONTROL SYSTEM FORGAS DISCHARGE DISPLAY PANELS The present invention is directed to a novel method and circuitry for controlling the border sites of a gaseous discharge display panel having inherent memory of the type as disclosed in, for example, Baker et al. U.S. Pat. No. 3,499,167.

As disclosed in the above-mentioned Baker et al. patent, there are a number of ways for conditioning the discrete information display discharge sites in such panels for operating at substantially uniform potentials. One such technique which is currently used is photon conditioning, which, as described in said Baker et al. patent, encompasses the maintaining in an on state of an entire row or column of the sites on the border of the panel in a fired or on condition during normal panel operation. The light from these discharge sites which are maintained on are masked or blocked from the normal viewing area or otherwise are not used for In the past, these sites were turned on and supplied with the sustainer potential from the same sustainer write wave forms,

FIG. 3 (A, B, C, D, E, F and G) illustrate the border erase wave forms,

FIG. 4 (A, B, C, D, E, F and G) illustrate the reduced rate border firing wave forms and FIG. 5 (A, a, c, D, E, F and G) illustrate the four axes border conditioning wave forms.

In FIG. 1, a gaseous discharge display panel 10 preferably of the type disclosed in Baker et a1. U.S. Pat. No. 3,499,167, filled with a neon-argon gas mixture (99.9 percent neon and 0.1 percent argon) as is disclosed in Nolan application Ser. No. 764,577 filed Oct. 2, 1968, and as is further modified by a dielectric or insulative overcoating (not shown) on the dielectric coatings of the aforementioned Baker et al. patent, a

lead oxide of a few hundred angstroms thick. Typically, the discharge gap distance in such panels is selected to be between 4 and 6 nuisf'l h paiiefi'fiiscofi stituted by a row conductor plate 11 and a column conductor plate 12 joined in spaced apart relation by a sources as the normal viewing or display area sites of Sealant (not h to p id h f re the panel.

The present invention provides a system for writing the border which has the capability of:

l. sustaining the border,

2. writing the border,

3. erasing the border during long idle periods to thereby minimize the efi'ect of aging,

4. border conditioning (all four' sides),

5. border firing at reduced frequency during long idle periods to minimize aging as an alternative to (3),. and

6. sustaining the border at a slightly higher voltage level (assuming a power supply is available other than the sustainer).

It has been found that writing the border cannot be accomplished in one sustainer cycle but requires time in the order of miliseconds range of the panel if the panel has'been idle for a long period of time. The affect of border aging, in addition,. can be overcome by sustaining the border at a higher level and as this aging becomes noticeable, this voltage can be adjusted to fire the border sites. As a result, the pull up to write to border has been eliminatedand this function is accomplished in accordance withthe invention by a programmable power supply control via the logic system.

The border sustainer supply system normally would be BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, advantages and features of the invention will'become more apparent in light of the following specification taken in conjunction I with the accompanying drawings wherein:

tioned discharge gap distances and a thin gas discharge chamber with the gaseous medium therein.

The row conductor plate 11 carries a row conductor array 13 in the writing or the information display area V and a row border-array l4 and 15 at 'the sides thereof. The column conductor plate 12 is identical, having a column conductor array 16 in the writing or viewing area of the data display area D and border or side conductors l7 and 18 respectively. (The border conductors are shown as spaced from their respective row and column conductors, but in fabrication of the panel can be one or more end conductors in each array. As indicated, the addressing circuits 20 and 21 for the row conductors and 22 and 23 for the column conductor, respectively, alternate or odd numbered conductors are driven by the odd addressing circuitry and the even conductors are driven'by the even conductor addressing circuits may be as disclosed in Leuck application Ser. No. 135,021 filed Apr. 19,1971 now U.S.

Pat. No. 3,665,400 and, as shown, float upon their respective sustainer sources for these conductors-in the panel. Except for the control times of the sustainers V, and V by control timing circuit 30, the panel and circuitry as described is, for the purposes of this application conventional.

THE INVENTION The present invention is directed to the circuitry for *manipulating the discharge sites located by the border be noted that the border conductors are provided with separate sustainer voltage sources V for the column border conductors l7 and 18 and V for the row border conductors l4 and 15 and like the standard sustainer generators VY and VX are controlled by control timing circuit 30. These timing features are illustrated in the wave form diagrams of FIGS. 2, 3, 4 and 5.

THE BORDER WRITE WAVE FORMS OF FIG. 2

FIG. 2A labeled V, is a square wave voltage wave form which is applied to the row conductors in array 13 via the X addressing circuits 21 and 22 (for the odd conductors 14-15 and 17-18. In this connection it will and even conductors, respectively) whereas the wave form of FIG. 23 labeled V,, is the voltage wave form which is applied to the column conductors 16 via the odd addressing circuitry 22 and the even addressing circuitry 23. The addressing circuits 20-21 and the addressing circuits 22 and 23 float upon, and are referenced to, their respective sustainer voltages. The wave form of the voltage applied to the gaseous medium at each discrete discharge site is shown in FIG. 2C which wave form labeled V, V,,. That is, the gas sees the difference between the voltage applied to these two conductor arrays. To turn on any-discrete site in the panel, a write voltage pulse (not shown) is algebraically added to the sustainer wave form voltage shown in FIG. 2C as by application of quarter select voltage pulses on a selected pair of intersecting row and column conductors which, algebraically added to the sustainer voltage at that instant is sufficient to initiate a discharge. The addressing of the discharge sites in the panel is, therefore, conventional.

In FIG. 3D the voltage wave form labeled V has a magnitude or value of V equal to the normal sustainer value V, (which is approximately 150 volts) plus approximately 90 volts so that for each of the border write sustainers V x8 and V the output voltage as determined by control and timing circuit 30 is V,,. This voltage, when algebraically added to the voltage of the crossing conductors in the column conductor array 16 (wave form 9, FIG. 2(8)), results in the voltage on the gas having the waveform illustrated in FIG. 2E, namely, V V which, is the difference between the voltage wave form in FIG. 2D and the voltage wave form in FIG. 2B. In a similar fashion, the waveform V shown in FIG. 2F is the output voltage of the border sustainer voltage generator in FIG. 1 labeled V The border conductors 17 and 18 for the Y axes have this voltage applied thereto and, combined with the row conductors in array 13 (V, asshown in FIG. 2A), results in the voltage on the gas at the discrete column border sites located by these conductor cross points, as shown in FIG. 2G, namely, V, V

The comer border sites located by the crossing of border conductors 14-15 with border conductors 17-18 have applied thereto a significantly larger voltages as is exemplified by the differences between the voltage wave form in FIG. 2D and the voltage wave form in FIG. 2F which will assure a reliable turn on of at least the corner border sites.

BORDER ERASE WAVE FORMS OF FIG..3

The border erase cycle and wave forms therefor is illustrated in FIG. 3 wherein FIGS. 3A, 3B andd 3C correspond to FIGS. 2A, 2B and 2C and are included to show the timing relationship of the border erase wave forms therewith. Power supplies 31 and 32 provide as a small direct current voltages as their outputs V, and V, plus A The arranged process consists essentially of modifying the widths of one of the pulses on the border sustainers. In this case, control timing generator 30 during the border erase cycle, sends a signal to the border sustainer generator to cause pulse 50, of FIG. 3D, to be narrower than the normal sustainer pulse width. Normal sustainer pulse width are about microsecond in width whereas the pulse width of sustainer erase pulse 50 is about 2 microseconds. This is sufficient to assure the removal of the wall voltage at the border sites. FIG. 3E shows the summation of the voltage at the sites located by the row conductors 13 (V and the border voltage V In a similar manner, the border sustainer voltage VX is caused to be at a level of V, A a and the wave form of the voltage located by the V border conductors 14 and 15 and the Y sustainer voltage V (V being minus V,,) FIG. 3G is shown. Because of the flexibility provided by having the additional power supply, as well as the control over the width of the sustainer pulses, it is possible to separately control the border sites. In the case just described, the border sites are erased during long idle times or when no information is to be displayed on the panel for a long period of time. In other words, during the long idle period in the display of information, it is desirable to minimize the aging effects at the border sites by erasing or turning the borders off. However, instead of erasing the border sites, this reduced aging effect can be achieved by simply reducing the freqeuncy or rate of discharges by control of the border sustainer generators V and V H by control timing 30. This, in effect, reduces the number of discharges per unit time at the border site with an attendant decrease in the adverse aging effects of aging at the border sites.

REDUCED BORDER FIRING WAVE FORMS OF FIG. 4

The above described method of reducing the frequency or rate of discharges is illustrated in FIG. 4. As shown, FIG. 4A, 4B and 4C correspond to FIGS. 2A, 2B and 2C, respectively. However, on FIG. 2C, the X marks the. point of site discharge. FIG. 4Dshows the column border sustainer V wherein the rate of the border sustainer is one-half the normal sustainer rate as shown in FIG. 2D. The alternate voltage pulses dotted at 91 FIGS. 2D and 4E, have been omitted. FIG. 4E is the voltage waveform of the gas appearing at the border sites located by the crossings of the column border conductors 17 and 18 with the row conductors in array 13 and FIG. 4G shows the voltage waveform at the crossing of the row conductor 14 and 15 with the column conductors in array 16. It will be noted that as compared to the border sustainer voltage wave forms (vyg and V in FIG. 2D and 2F, it will be noted that the rate is approximately one-half the normal sustainer rate. Therefore, the number of discharges is reduced to one-half.

Thus, by not supplying a sustainer pulse at the normal time interval indicated in dotted lines at 91 in the column sustainer voltage V (FIG. 4D, there is no discharge during that time interval and, since the polarity of the wall voltage remains the same as on the previous discharge or firing as indicated at 93 at FIG. 4E, the

next succeeding discharge which would of occurred at point 94 does not occur (because the wall voltage is in the same direction as the applied voltage). Accordingly,the rate of discharges is significantly reduced thereby reducing the adverse effects of aging on the panel. A similar action takes place in connection with the border sites located by border conductors 14 and 15 at crossing points of the conductors in conductor array 16.

This process and techniques of reducing the number of firings so as to eliminate or minimize some of the adverse aging effects is an alternative procedure to the procedure of turning off the border sites.

FOUR AXlS BORDER CONDITIONING WAVE FORMS OF FIG. 5

in this embodiment, write signals I are applied to a selected site to enter information to the panel and effect a discharge (K) at that site. The border sustainer sources V and V are shifted in the direction of the arrows shown in FIG. 5 to coincide with the leading edge of the address pulses l The border sites then fire at the same time as the leading edge of the address signal pulses l Thus, by four axes border conditioning, it is intended to mean that the sites are on border and the conductors in each array have potentials on the normal row-column conductors the display area sites are more reliably conditioned by turning the border discharges to occur close in time thereto. Note that at times other than the write intervals shown, the V border sustainer potential is the same as the normal sustainer potential V and that the row border sustainer potentials V is the same as the row sustainer VX- trolling the border sites of gaseous discharge display panels which are maintained on for photonic conditioning purposes and provides a border writer for sustaining the border which is independent of a normal sustainer and which is also controllable by the logic signals, permitting writing and erasing of the border and conditioning on all four sides, border firing at reduced frequency or rate which, like erasing the border during idle periods, minimizes the aging effects on the border conductors and, sustaining the border at slightly higher voltage levels which may be reduced during operation of the panel as the aging processes proceed.

Although the invention has been described in its preferred embodiments, it is clear that the basic principles thereof are applicable to other embodiments obvious to those skilled in the art and it is intended that the claims encompass such obvious embodiments.

What is claimed is:

l. A method of operating a gas discharge data display panel of the type having an insulatingly coated row-conductor array on a first support plate, a insulatingly coated column conductor array on a second support substrate, means joining said plates in spaced apart relation with a gaseous discharge medium between said coated conductor arrays, a selected number of conductors in each said array locating border discharge sites which are used asnon-data display areas,

' and wherein the'operating potentials tosaid conductor arrays includes aperiodic voltage for sustaining discharges once initiated, said periodic sustainer voltage being of a magnitude insufficient to initiate a discharge at any site but of sufficient magnitude to maintain discharges once initiated at any site, and a data entering discharge initiating signal voltage for algebraic addition to said sustainer voltage potential,

the improvement comprising,

supplying a separate sustainer potential to said border conductors,

controlling said separate sustainer potential to control the on condition of said border sites, including the steps of increasing the voltage level of said border sustainer voltage above a selected level for a selected time interval to turn the border on.

Thus, the invention achieves the objectives of con- 2. The invention defined in claim 1 including the step of minimizing the aging of said border sites by modifying the rate of discharge at said border sites during long periods of no addressing to the normal viewing area of said panel.

3. The invention defined in claim 1 including the step of minimizing the aging of said border sites by applying an erase signal voltage to said border sites preceeding long periods of no information being displayed in the normal viewing area of said panel.

4. The invention defined in claim 1 wherein said border sustainer voltage level is higher than the normal sustainer voltage level to said row-column conductor arrays, including lowering the level of said sustainer voltage over a long period of use.

5. The invention defined in claim 4 wherein said higher voltage level is 3l0 volts above said normal sustainer voltage level.

6. The invention defined in claim 1 including the step of shifting the time of said border sustainer voltage so that the discharge border sites occur near the time of the leading edge of information write pulses to said row-column conductor arrays.

7. In a gaseous discharge display panel having rowcolumn conductor arrays non-conductively coupled to a gas discharge medium in a chamber space between said row and said column conductor arrays and row and column border conductor arrays cooperating with the ends of the conductors in the row-column conductor arrays to define border sites which, for the purpose of photon conditioning of information display sites in the panel, are on during the entry of information to be displayed on said panel, the improvement of said panel which comprises,

a separate controllable border sustainer voltage supply means connected to said border conductor arrays,

control timing circuit means for controlling said border sites by controlling said controllable border sustainer voltage supply,

said control timing circuit means including providing a control signal for causing the output voltage level of said border sustaining supply means to rise above a predetermined level, which predetermined level is insufficient in the absence of immediately previous discharges at said border sites to sustain discharges thereat, and for a selected time interval to at least turn 'on said border sites.

8. The invention defined in claim 7 wherein controllable border sustainer supply includes means for supplying a plurality of voltage level output voltages,

and

means connecting one of said output voltages to said border conductor.

9. The invention defined in claim 7 said control timing circuit means including means for relatively shift- 

1. A method of operating a gas discharge data display panel of the type having an insulatingly coated row-conductor array on a first support plate, a insulatingly coated column conductor array on a second support substrate, means joining said plates in spaced apart relation with a gaseous discharge medium between said coated conductor arrays, a selected number of conductors in each said array locating border discharge sites which are used as non-data display areas, and wherein the operating potentials to said conductor arrays includes a periodic voltage for sustaining discharges once initiated, said periodic sustainer voltage being of a magnitude insufficient to initiate a discharge at any site but of sufficient magnitude to maintain discharges once initiated at any site, and a data entering discharge initiating signal voltage for algebraic addition to said sustainer voltage potential, the improvement comprising, supplying a separate sustainer potential to said border conductors, controlling said separate sustainer potential to control the on condition of said border sites, including the step of increasing the voltage level of said border sustainer voltage above a selected level for a selected time interval to turn the border on.
 2. The invention defined in claim 1 including the step of minimizing the aging of said border sites by modifying the rate of discharge at said border sites during long periods of no addressing to the normal viewing area of said panel.
 3. The invention defined in claim 1 including the step of minimizing the aging of said border sites by applying an erase signal voltage to said border sites preceeding long periods of no information being displayed in the normal viewing area of said panel.
 4. The invention defined in claim 1 wherein said border sustainer voltage level is higher than the normal sustainer voltage level to said row-column conductor arrays, including lowering the level of said sustainer voltage over a long period of use.
 5. The invention defined in claim 4 wherein said higher voltage level is 3-10 volts above said normal sustainer voltage level.
 6. The invention defined in claim 1 including the step of shifting the time of said border sustainer voltage so that the discharge border sites occur near the time of the leading edge of information write pulses to said row-column conductor arrays.
 7. In a gaseous discharge display panel having row-column conductor arrays non-conductively coupled to a gas discharge medium in a chamber space between said row and said column conductor arrays and row and column border conductor arrays cooperating with the ends of the conductors in the row-column conductor arrays to define border sites which, for the purpose of photon conditioning of information display sites in the panel, are on during the entry of information to be displayed on said panel, the improvement of said panel which comprises, a sEparate controllable border sustainer voltage supply means connected to said border conductor arrays, control timing circuit means for controlling said border sites by controlling said controllable border sustainer voltage supply, said control timing circuit means including providing a control signal for causing the output voltage level of said border sustaining supply means to rise above a predetermined level, which predetermined level is insufficient in the absence of immediately previous discharges at said border sites to sustain discharges thereat, and for a selected time interval to at least turn on said border sites.
 8. The invention defined in claim 7 wherein controllable border sustainer supply includes means for supplying a plurality of voltage level output voltages, and means connecting one of said output voltages to said border conductor.
 9. The invention defined in claim 7 said control timing circuit means including means for relatively shifting the time of firing of said border sites to a time just preceeding the addressing of information to be displayed at said information display sites.
 10. The invention defined in claim 9 wherein said information pulses on selected row-column conductors in said arrays are relatively timed to occur with the leading edge of the border sustainer voltage.
 11. The invention defined in claim 7 said control timing circuit means including means for controlling said border sustainer voltage supply to turn all said border sites off during long idle periods of addressing information display sites in said panel. 